Factors To Improve Upon & Measure Your Site’s Credibility:

In-Links: The search engines see in-links (links leading to your website from external sites) as signs of your trustworthiness. In-links are the virtual equivalent of someone “vouching” for your site. The more successful and credible the other site, the better you look to Bing and Google.
Out-links: Contrary to in-links, out-links are the links on your site that link to external sites. If your links are broken or the external site is irrelevant or outdated, your search rankings can take a hit.
A clean, error-free site: Broken/missing images, spelling mistakes, or 404 errors are all poor signs of a site’s credibility.
Traffic: Theoretically, the more traffic you get, the more relevant you are to searchers.

An easy-to-navigate website: A site that’s easy to navigate can reassure new visitors that your site contains the information they need. If your site is difficult or confusing to navigate, your site’s bounce rate (the percentage of users who immediately leave your site) will be higher— indicating to the search engines that your site wasn’t a successful match for those search queries.
An XML sitemap: Just like your site must be easy to navigate for humans, it should be similarly easy to navigate for the search spiders, too. An XML sitemap acts as a “road map” that leads bots down each interconnected page of your site, allowing them to index your page more quickly and accurately. Most websites have two sitemaps: a text-based list of pages within the sites and an .xml file for the spiders.